JP3919528B2 - toothbrush - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toothbrush in which at least one of a head part, a neck part, and a grip part is composed of a hard resin part and a soft resin part.
[0002]
[Prior art]
Conventionally, in a toothbrush in which any of the head part, the neck part, and the grip part is composed of a hard resin part and a soft resin part, a thermoplastic elastomer (hereinafter referred to as “TPE”) is generally used for the soft resin part. ing.
[0003]
The purpose of combining the soft resin part with the hard resin part is to improve the fit and resilience when gripping the handle in the case of the grip part, and the difficulty of slipping. It was to have it.
[0004]
TPE is a thermoplastic resin that has rubber elasticity at room temperature, and consists of a soft segment having rubber elasticity and a hard segment that prevents plastic deformation. In the case of a toothbrush, styrenic TPE Or olefinic TPE is used.
[0005]
In addition, polypropylene resin is often used for the hard resin part of toothbrushes in terms of flexural modulus, moldability, chemical resistance, price, etc., but styrene-based TPE and olefin-based TPE have adhesion to polypropylene resin. There are also features such as good.
[0006]
However, a rubber component is used in the conventional TPE soft segment, and the rubber component is easily dissolved in an organic solvent, which causes a problem in chemical resistance.
[0007]
In addition, many commercially available toothbrushes have a plurality of brush bundles fixed to a head portion made of a hard resin integrated with a gripping portion and a neck portion. Therefore, although the brush is bent during brushing, the head portion itself is movable. Therefore, when emphasizing ease of brushing of the back teeth, there was a problem that the front side of the front teeth was slightly hard to polish.
[0008]
On the other hand, as an example of a movable head in which the head portion is composed of a hard resin portion and a soft resin portion, there is one described in JP-T-6-507792. In the case of this movable head, the brush bundle is only a hard resin. The design of the flocking specification was limited.
[0009]
Also, JP-A-6-505895, JP-A-9-19323, JP-T-10-502846, JP-T11-513924, JP-T2000-502582, JP-T-2000-50369. Examples of other movable heads are also disclosed in Japanese Laid-Open Patent Publication No. 2000-503570, No. 2000-515404, No. 2000-516507, and WO 98/58562. In both cases, the flocked part was divided by the movable part, and this also had restrictions on the design of the flocked specification.
[0010]
[Problems to be solved by the invention]
The present invention was made based on the above circumstances, and the object of the present invention is a toothbrush in which at least any of the head part, the neck part, and the grip part is composed of a hard resin part and a soft resin part. The soft resin part is to provide a toothbrush excellent in chemical resistance. Further, another object is to provide a toothbrush in which a part or the whole of the head part can be moved during brushing, the head part has excellent elasticity, and the brush tip easily fits in the dentition. .
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a toothbrush in which at least any one of a head part, a neck part, and a grip part is composed of a hard resin part and a soft resin part. An olefin copolymer or a mixture thereof, an ethylene / methyl methacrylate / copolymer or a mixture thereof, an ethylene / acrylic acid ester / maleic anhydride terpolymer or a mixture thereof, An ethylene octene copolymer is used as the α-olefin copolymer.
[0012]
In particular, when the head part is composed of a hard resin part and a soft resin part, and the resin is used as the soft resin part, the head part is excellent in elasticity and at the same time the brush tip easily fits in the dentition. A toothbrush can be obtained.
[0013]
The soft resin used in the present invention described above has a structure including a long chain branch having a length close to the main chain in a uniform polymer and has flexibility. Unlike normal TPE, since it does not contain a rubber component or an oil component, there is no problem that the rubber component or the oil component is dissolved in an organic solvent as in the prior art.
[0014]
Among TPE, styrene-based TPE and olefin-based TPE are cheaper than other TPEs, but ethylene-α-olefin copolymers, especially ethylene-octene copolymers, are more advantageous in terms of price. Have.
[0015]
The ethylene / α-olefin copolymer is a generic name for copolymers of ethylene and an olefin having a double bond at the α-position, and α-olefin monomers having 3 to 10 carbon atoms are used. It is done. Specifically, ethylene butene copolymer, ethylene pentene copolymer, ethylene hexene copolymer, ethylene heptene copolymer, ethylene 3-methyl-1-pentene copolymer, ethylene octene copolymer Copolymers, ethylene decene copolymer, etc.
[0016]
When forming a toothbrush handle consisting of a head, neck, and gripping part with a two-color molding method consisting of a hard resin part and a soft resin part, using cheap and chemically stable polypropylene as the hard resin As the soft resin part, it is preferable to use an ethylene / α-olefin copolymer or a mixture thereof, and it is more preferable to use an ethylene / octene copolymer or a mixture thereof.
[0017]
In order to mold the toothbrush handle by the two-color molding method, first, a hard resin portion is molded by injection molding using a first injection mold, and the molded hard resin portion is further molded. After being inserted into the injection mold 2, the soft resin is injection molded to form the soft resin portion.
[0018]
On the other hand, depending on the structure of the toothbrush, first, a soft resin is injection-molded using the first injection mold to form a soft resin portion, and this molded soft resin portion is further injected into the second injection mold. After inserting into the molding die, the hard resin portion may be molded by injection molding of a hard resin.
[0019]
In these cases, it is necessary to form a flocking hole for flocking a brush or a bundle of brushes on the flocking surface of the head portion of the toothbrush handle to be molded. Therefore, a mold for forming a flocking hole in advance in the injection mold Although the mold pin is provided in the mold, when the head portion is composed of a hard resin and a soft resin, the mold pin is preferably provided across the hard resin portion and the soft resin portion.
[0020]
Thus, when the mold pin is provided across the hard resin portion and the soft resin portion, the flocked hole is formed across the hard resin portion and the soft resin portion, so that the brush or the bundle of brushes fixed to the flocked hole is formed. It is possible to improve the flocking strength, which is more preferable. Of course, after the toothbrush handle is formed by the above method without using the mold pin, the flocked hole may be formed later by a drill or a laser.
[0021]
In order to plant a brush or a bundle of brushes on the head part of the toothbrush handle obtained as described above, the flat line implantation method using a metal piece (flat line) or the lower end of the brush or the bundle of brushes is melted, A heat fusion method (see Japanese Patent Application Laid-Open No. 60-241404) in which the melted portion is pressed into the head portion of the toothbrush handle in a molten state and fixed, and further a brush or a brush bundle protruding into the mold After forming the molten lump by heating the lower end of the in-mold method (Japanese Patent Laid-Open No. 61-268208, in which a molten lump portion of a brush or a bundle of brushes is buried by injecting molten resin into the mold) For example, see Japanese National Publication No. 9-512724.
[0022]
In the case of the in-mold method, the above-described mold pin for forming the flocked hole is not necessary, but from the viewpoint of flocking strength, the fixed brush or brush bundle is embedded across the hard resin portion and the soft resin portion. It is preferable to do this.
[0023]
In the case of the in-mold method, the size of the hair bundle molten lump is not particularly limited, but a plurality of brushes constituting the hair bundle are dropped when the toothbrush is brushed (one missing). It is formed for the purpose of integrating the end portions, and by setting the cross-sectional area of the hair bundle molten mass to be larger than the cross-sectional area of the hair bundle, the flocking strength of the hair bundle can be increased.
[0024]
Although there is no limitation in particular about the softness of the soft resin used in this invention, It is preferable to select suitably according to the site | part of the toothbrush to be used. The hardness of the soft resin is preferably about 50 to 100 in the test method ASTM D-2240: Shore A.
[0025]
In addition, the soft resin portion used in the present invention may be a mixture of another resin such as a polyethylene resin as well as the above-mentioned soft resin alone. By mixing and using polyethylene resin, there is an advantage that hardness and heat-resistant temperature can be appropriately selected and selected. In particular, when the hard resin is a polypropylene resin, the polyethylene resin alone does not adhere, but when it is mixed with a soft resin, it adheres well.
[0026]
When the soft resin is formed in the head portion, one or a plurality of soft resin portions may be formed. In the case of a plurality of soft resin portions, the size may be the same or different. Further, the soft resin portion may extend over the entire head portion or may be unevenly distributed. In the case of uneven distribution, when the number of the soft resin portion is one, the soft resin portion is located between the center of the head portion and the tip of the head portion, more preferably from the neck side side root of the head portion toward the tip of the head portion. The position should be about 2/3.
[0027]
In the case of uneven distribution, when the soft resin portion has a plurality of the same size, the central soft resin portion among the plurality of soft resin portions is between the head portion center and the head portion tip, more preferably the head portion. It is preferable that the position of the head part is about 2/3 of the total length of the head part from the base part of the head part toward the tip of the head part.
[0028]
Further, in the case of uneven distribution, when the soft resin portion has a plurality of irregular sizes, the largest soft resin portion among the plurality is between the center of the head portion and the tip of the head portion, more preferably the head portion. It is preferable that the position is about 2/3 of the total length of the head portion from the neck side base toward the tip of the head portion.
[0029]
The hard resin only needs to have a resin hardness that is relatively harder than that of the soft resin. For example, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polymethyl methacrylate, cellulose propionate, polyurethane, polyamide, ABS, or the like is used. However, polypropylene is more preferable in terms of cost.
[0030]
The material of the brush is not particularly limited. For example, polyamide (nylon 6-10, nylon 6-12, etc.) or polyester (PBT, PET, etc.) is used.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a first embodiment of a toothbrush according to the present invention.
In the first embodiment, the flocked surface side of the head portion 1 is constituted by the hard resin portion 2, and the soft resin portion 3 is arranged on the back side thereof. It is embedded across the soft resin portion 3.
[0032]
The hard resin portion 2 is integrally formed with the neck portion 5 and a grip portion (not shown), and polypropylene is used as the hard resin. The physical properties of the used polypropylene resin are a flexural modulus of 19000 Kgf / cm ² (JIS K7203) and Rockwell hardness 112 (JIS K7202).
[0033]
The soft resin portion 3 is made of a single ethylene octene copolymer and has a surface hardness of 94 (ASTM D-2240 Shore A).
[0034]
In the case of the toothbrush having such a configuration, the soft resin portion 3 is made of ethylene octene copolymer, and therefore has excellent chemical resistance. Furthermore, since the head portion 1 has a two-layer structure of the hard resin portion 2 and the soft resin portion 3, the head portion 1 is excellent in elasticity, and the bristles of the brush bundle 4 can easily fit in the dentition, A toothbrush with excellent usability can be obtained.
[0035]
FIG. 2 shows a second embodiment of the toothbrush according to the present invention.
In the second embodiment, as in the first embodiment, the flocked surface side of the head portion 1 is configured with the hard resin portion 2, and the soft resin portion 3 is disposed on the back side thereof. The head part 1 is bent and inclined by about 20 degrees toward the flocked surface side. In addition, the same code | symbol was attached | subjected and shown to the same part as 1st Embodiment.
[0036]
In the case of the second embodiment, the hard resin portion 2 is made of polypropylene resin as in the first embodiment, and the physical properties thereof are the same as those in the first embodiment.
[0037]
On the other hand, the soft resin portion 3 is made of a mixture of ethylene octene copolymer and polyethylene resin (weight ratio 70:30), and the ethylene octene copolymer has a surface hardness of 75 (ASTM D-2240: Shore A) and polyethylene resin. The bending elastic modulus is 230 (JIS K7203: MPa).
[0038]
Thus, when the soft resin part 3 is comprised with the mixture of ethylene octene copolymer and polyethylene resin, the hardness and heat-resistant temperature of the soft resin part 3 can be set more appropriately by adjusting the weight ratio. .
[0039]
In addition, when the hard resin part 2 is made of polypropylene resin, the polyethylene resin alone does not adhere to the polyethylene resin, but it can be adhered well by mixing with the ethylene / octene / copolymer resin. A decrease in the adhesive strength of the resin part 3 can also be prevented.
[0040]
FIG. 3 shows a third embodiment of the toothbrush according to the present invention.
In the third embodiment, contrary to the first and second embodiments, the soft resin portion 3 is formed on the flocked surface side of the head portion 1 and the hard resin portion 2 is formed on the back surface side thereof. This is an example. The materials and physical properties of the hard resin portion 2 and the soft resin portion 3 are the same as those in the first embodiment described above, and the details thereof are omitted.
[0041]
Also in the case of the third embodiment, the soft resin portion 3 is excellent in chemical resistance and the head portion 1 is excellent in elasticity as in the case of the first embodiment. Can easily fit into the dentition, and can be a toothbrush with excellent usability.
[0042]
In addition, although the said embodiment illustrated the case where the ethylene octene copolymer and its mixture were used as the soft resin part 3, instead of these, other ethylene * alpha-olefin copolymer, for example, ethylene butene, was used. Copolymer, ethylene pentene copolymer, ethylene hexene copolymer, ethylene heptene copolymer, ethylene 3-methyl-1-pentene copolymer, ethylene decene copolymer and mixtures thereof, and It can also be realized in the same manner by using an ethylene / methyl methacrylate / copolymer and a mixture thereof, an ethylene / acrylic acid ester / maleic anhydride terpolymer and a mixture thereof.
[0043]
【The invention's effect】
As described above, according to the present invention, in a toothbrush in which at least any one of the head portion, the neck portion, and the grip portion is composed of a hard resin portion and a soft resin portion, as the soft resin portion, ethylene · α- Olefin copolymer or mixture thereof, ethylene / methyl methacrylate / copolymer or mixture thereof, ethylene / acrylic acid ester / maleic anhydride terpolymer or mixture thereof is used, so it has excellent chemical resistance. A toothbrush can be obtained.
[0044]
In particular, when the head part is composed of a hard resin part and a soft resin part, and the resin is used as the soft resin part, the head part can move elastically during brushing, so it has excellent adhesion to the dentition, Excellent effects such as good contact with teeth and gums are obtained.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of a toothbrush according to the present invention and is a schematic cross-sectional view of a head portion and a neck portion.
FIG. 2 is a schematic cross-sectional view of a head portion and a neck portion, showing a second embodiment of a toothbrush according to the present invention.
FIG. 3 shows a third embodiment of a toothbrush according to the present invention and is a schematic cross-sectional view of a head portion and a neck portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Head part 2 Hard resin part 3 Soft resin part 4 Brush bundle 5 Neck part

Claims (2)

In a toothbrush in which at least one of the head part, the neck part, and the grip part is composed of a hard resin part and a soft resin part,
The soft resin part is any one of an ethylene / α-olefin copolymer or a mixture thereof, an ethylene / methyl methacrylate / copolymer or a mixture thereof, an ethylene / acrylic acid ester / maleic anhydride terpolymer or a mixture thereof. The toothbrush characterized by becoming. The toothbrush according to claim 1, wherein an ethylene / octene copolymer is used as the ethylene / α-olefin copolymer.

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